JP-2009-236797A discloses a fluid level measurement apparatus. As shown in FIG. 3 of JP-2009-236797A, the fluid level measurement apparatus includes a magnetoelectric element as a magnetoelectric fluid level sensor, a circuit, and an IC. A voltage between the output terminal and the ground terminal of the magnetoelectric element changes with the fluid level. The output of the magnetoelectric element is inputted to the circuit so that the circuit can generate a detection voltage. The IC receives the detection voltage from the circuit and calculates the fluid level based on the detection voltage.
JP-2010-78320A discloses another fluid level measurement apparatus including an electrical resistance element as an electrical resistance fluid level sensor. An electrical resistance of the electrical resistance element changes with the fluid level.
Typically, an electrical resistance fluid level sensor using an electrical resistance element as disclosed in JP-2009-236797A costs less than a magnetoelectric fluid level sensor using a magnetoelectric element as disclosed in JP-2009-236797A. However, depending on types of fluid, the detection accuracy of the electrical resistance fluid level sensor is less than that of the magnetoelectric fluid level sensor. Therefore, it is preferable to use different types of fluid level sensors according to types of fluid.
In JP-2009-236797A, the circuit for generating the detection voltage is specialized to process the output of the magnetoelectric fluid level sensor. Therefore, if the magnetoelectric fluid level sensor is replaced with the electrical resistance fluid level sensor as disclosed in JP-2009-236797A, the circuit cannot generate the detection voltage accurately. As a result, the IC cannot calculate the fluid level accurately.